Method for forming photo-defined micro electrical contacts

ABSTRACT

A method of manufacturing a probe test head for testing of semiconductor integrated circuits includes: defining shapes of a plurality of probes as one or more masks; a step for fabricating the plurality of probes using the mask; and disposing the plurality of probes through corresponding holes in a first die and a second die. The step for fabricating the plurality of probes may include one of photo-etching and photo-defined electroforming.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation-In-Part of U.S. patent applicationSer. No. 10/027,146, filed Dec. 20, 2001 U.S. Pat. No. 6,906,540, whichclaims the benefit of U.S. Provisional Patent Application Ser. No.60/323,651, filed Sep. 20, 2001, both of which are incorporated byreference herein in their entirety.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

This invention relates to a method for the manufacture of miniaturemicro probes or electrical contacts for use in testing semiconductorchips.

(2) Description of the Related Art

It is known in the art of testing probe cards for electrical continuityto perform such tests using probes made by mechanically forming astraight piece of fine wire into a desired shape so as to provide thenecessary size and spring force. FIGS. 1-3 show a conventional “Cobra™”probe test head produced by Wentworth Laboratories, Inc. of Brookfield,Conn. Such probe heads consist of an array of probes 64 held betweenopposing first (upper) 42 and second (lower) 44 dies. Each probe hasopposing upper and lower ends. The upper and lower dies 42, 44 containpatterns of holes corresponding to spacing on an integrated circuitcontact pad spacing designated herein as lower die hole pattern andupper die hole pattern. The upper end of each of the probes is retainedby the upper die hole pattern, and the lower end of each of the probespasses through the lower die hole pattern and extends beyond the lowerdie 44 to terminate in a probe tip. With reference to FIG. 13, there isillustrated the additional inclusion of mounting film 1301. Mountingfilm 1301 is typically formed from a suitable polymeric dielectric suchas mylar and holds the etched probes 81 in place. For Cobra™ styleprobes, the lower die hole pattern is offset from that in the upper die42, and the offset is formed into the probe such that the probe actslike a spring. Returning to FIGS. 1-3, when the test head is broughtinto contact with a wafer to be tested, the upper end of the proberemains predominately stationary, while the lower end compresses intothe body of the test head. This compliance allows for variations inprobe length, head planarity, and wafer topography. The probe istypically formed by swaging or stamping a straight wire to produce thedesired probe shape and thickness. This swaging process flattens andwidens the center, curved portion of the probe in order to achieve adesired force per mil of probe deflection.

The lower and upper ends of the swaged area also prevent the probe fromextending too far through the dies. In a conventional probemanufacturing process, the probes are formed from a straight piece ofwire, typically of beryllium-copper alloy. Custom tooling is used foreach probe size and design. The tooling stamps and forms the centerportion of the wire to achieve the desired shape and thickness, therebygenerating a desired spring rate.

With reference to FIG. 9 there is illustrated cross sectional renderingsof a wire used in the prior art to produce probes. Cross section 90illustrates the generally circular form of the pre-stamped wire. Crosssection 91 illustrates the generally elliptical shape of a stamped andtooled wire. The cross sectional areas of both cross section 90 andcross section 91 are substantially the same. With reference to crosssection 91, the stamped wire forming the probe has a width 95 ofapproximately 7 mil (one mil equals 0.001 inch) and a height 97 ofapproximately 1.8 mils. When assembled in a probe head configuration itis preferable to maintain at least a 1 mil separation between theplurality of probes used in the probe head. As a result of width 95being approximately 7 mils and requiring a 1 mil separation,conventional probes arranged in a probe head are typically spaced oneprobe every 8 mils. The wire is then cut to length, and the desiredprobe tip geometry is ground on the end of the probe. The tolerance onthe overall length of the finished probes is +/−0.002″. Because this istoo large a variance between probes for proper testing, the probes areassembled into a probe head and the entire array of probes is lapped toachieve a more uniform probe length.

Conventional stamping processes used to form probes often result inresidual stresses in the probes which may cause reduced fatigue life.Because these residual stresses can change over time, changes in probestiffness may arise. In addition, changes in the requirements for probesrequire retooling. Such retooling contributes to a high cost for probesmanufactured in such a fashion and require a substantial lead timebefore such probes are available. It is also the case that mechanicallyfashioned probes are more difficult to redesign as their construction isclosely tied to the mechanical means by which they are created.

There therefore exists a need for a method of manufacturing such probesthat avoids the problems which arise from mechanical formation. There isfurther a need for such a method substantially amenable to producingprobes of different designs absent a protracted retooling process.

BRIEF SUMMARY OF THE INVENTION

One aspect of the instant invention is drawn to a method of fabricatinga plurality of micro probes comprising the steps of defining the shapesof a plurality of probes as one or more masks, applying a photoresist tofirst and second opposing sides of a metal foil, overlaying one each ofthe masks on opposing first and second sides of the metal foil, exposingthe photoresist to light passed through each of the masks, developingthe photoresist, removing a portion of the photoresist to expose aportion of the metal foil, and applying an etcher to the surface of themetal foil to remove the exposed portion to produce a plurality ofprobes.

Another aspect of the instant invention is drawn to a method offabricating a plurality of micro probes comprising the steps of:defining the shapes of a plurality of probes as a mask; applying aphotoresist to a side of a first metal material; overlaying said mask onsaid side of said metal first material; exposing said photoresist tolight passed through said mask; developing said photoresist; removing aportion of said photoresist to expose a portion of said first metalmaterial; electroforming a second metal material on said exposedportions of said first metal material; and removing said second metalmaterial to produce a plurality of probes.

Another aspect of the invention is drawn to a micro probe manufacturedaccording to the aforementioned method wherein the micro probe comprisesa probe base having a generally uniform thickness bounded by a pluralityof edges and extending for a substantially straight length in a plane, aprobe shaft connected to the probe base the probe shaft of the generallyuniform thickness, bounded by a plurality of edges, and extending alonga curved expanse within the plane, a probe end connected to the probeshaft the probe end of the generally uniform thickness, bounded by aplurality of edges, and extending for a substantially straight distancewithin the plane the straight distance being approximately parallel tothe straight length, and a scallop running substantially around aperiphery comprised of the edges of the probe base, the probe shaft, andthe probe end.

Yet another aspect of the invention is drawn to a probe test headcomprising a first die comprised of first and second opposing planarsurfaces the first die further comprising a pattern of first die holesextending through the first die in a direction perpendicular to both ofthe first and second planar surfaces, a second die comprised of thirdand forth opposing planar surfaces the second die further comprising apattern of second die holes corresponding to the pattern of first dieholes the second die holes extending through the second die in thedirection wherein the third planar surface is arranged in planar contactwith the second planar surface such that the second die holes are offsetfrom the first die holes in a substantially uniform direction, and aplurality of probes one each of the probes extending through one of thefirst die holes and one of the second die holes the probes having asurface finish commensurate with having been formed by electroforming oretching.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective illustration of a probe test head known in theart.

FIG. 2 is a perspective illustration of a cross section of a probe testhead known in the art.

FIG. 3 is a cross section of a portion of a probe test head known in theart.

FIG. 4 is a front view of a probe of the present invention.

FIG. 5 is a side view of a probe of the present invention.

FIG. 6 is an isometric view of a probe of the present invention.

FIG. 7 is a photograph of a mask of the present invention.

FIG. 8 is a photograph of a standard probe known in the art and aphoto-defined probe of the present invention.

FIG. 9 is a cross sectional illustration of a probe known in the artboth before and after machining.

FIG. 10 is a cross sectional diagram of a probe of the present inventionafter etching.

FIG. 11 is a perspective illustration of the tip of a probe of thepresent invention.

FIG. 12 is a perspective illustration of the configuration of the masks,the photoresist, and the flat stock of the present invention prior toetching.

FIG. 13 is a cross section of a portion of a probe test head of thepresent invention.

DETAILED DESCRIPTION

The present invention is drawn to a method of manufacturing probes in away that provides improved uniformity while lowering the manufacturingcost of the probes. The probes are manufactured using a process in whichthe probes are photo-defined. By “photo-defined” it is meant that thedesired shape of the probes is first specified as an image in graphicform, and the image is used to make a mask having a repeating pattern ofthe desired probe profile. The mask is then used along with aphotoresist in a photo-etching or photo-defined electroforming process,rather than a mechanical stamping process prevalent in the art.

With reference to FIG. 8, there is illustrated a photo-defined probe 81of the present invention and a standard probe 83 known in the art. Thedesired shape of the probe 81 of the present invention is firstspecified as an image in graphic form, and the image is used to make aglass mask having a repeating pattern of the desired probe profile. FIG.7 illustrates a sample of such a mask 73. Mask 73 is comprised of aplurality of probe shapes 72 and dark spaces 71. The probe shapes 72define the areas corresponding to the photo-defined probes of thepresent invention and are constructed so as to allow light to passsubstantially unimpeded through probe shapes 72. Dark spaces 71 extendpredominantly between probe shapes 72 and serve to substantiallydifferentiate one probe shape 72 from each other probe shape 72 on mask73.

In a first embodiment of the present invention, the mask 73 is used in aprocess wherein the probes 81 are etched from thin metal flat stock,typically of Beryllium-Copper alloy. In a second embodiment of thepresent invention, a stainless steel mandrel is formed using the mask73, and the probes 81 are in turn electroformed on the mandrel from athin metal, typically of Nickel or Nickel-Cobalt alloy.

Embodiment 1—Etched Probes

With reference to FIG. 12, there is illustrated the probe configuration1205 employed to produce the etched probes of the first embodiment ofthe present invention. Flat stock 1201 is a predominantly planar sheetof thin metal having opposing planar surfaces. Flat stock 1201 has awidth corresponding to the desired width of the finished probe. Apreferred width of the flat stock 1201 is approximately 3 mil.

A photoresist 1001 is then applied to both opposing planar surfaces offlat stock 1201. Two identical masks 73 are then fastened to opposingsides of flat stock 1201 with one side of each mask 73 in contact withthe photoresist 1001 covering a single side of flat stock 1201. The twomasks 73 are aligned such that any one feature in either mask 73corresponding to an identical feature in the other mask 73 is in exactalignment across an axis perpendicular to the expanse of the planarsurfaces of flat stock 1201. Light is then applied to each mask 73effective to expose the photoresist 1001 disposed between each mask 73and flat stock 1201. Both masks 73 are then separated from probeconfiguration 1205. After exposure of the photoresist 1001 to light, thephotoresist 1001 is developed and rinsed. As a result of rinsing,exposed photoresist 1001 corresponding to a probe shape 72 on mask 73remains bonded to flat stock 1201, while unexposed portions ofphotoresist 1001 corresponding to a dark space 71 is rinsed off of andout of contact with flat stock 1201.

An etcher is then applied at substantially the same time to bothsurfaces of flat stock 1201. The etcher begins to dissolve flat stock1201 in a direction extending from the outer surfaces of flat stock 1201along an axis perpendicular to the planar expanse of flat stock 1201 anddirected into flat stock 1201 from each opposing planar surface. Oneattribute of applying etcher to a photoresist affixed to a metalsubstrate in order to dissolve the metal substrate is the presence ofunder cutting. As used herein, “undercutting” refers to the tendency ofan etcher applied to dissolve metal to deviate from an etched pathextending perpendicular to the surface to which the etcher was applied.Specifically, the etcher tends to extend outward as it travels into themetal.

With reference to FIG. 10, there is illustrated the effect onundercutting on the etched probes of the present invention. FIG. 10 is across sectional view of the etched probes of the present invention afterapplying the etcher. As can be seen, the etcher has effectively removedthe metal comprising flat stock 1201 from the area bordered by undercut1005 and etch limit 1007. As is illustrated, undercut 1005 extends froman exterior surface of flat stock 1201 towards the interior of flatstock 1201. Note that undercut 1005 deviates slightly from perpendicularaxis 1009 running perpendicular to the surfaces of flat stock 1201. Etchlimit 1007 is the boundary designating the extent to which the etcherremoves flat stock 1201 up until the etcher is neutralized or otherwiserendered incapable of further etching. Because the etcher etches at asubstantially constant rate and follows a path along undercut 1005deviating from perpendicular axis 1009, the resultant etch limit 1007forms a gently curving boundary. By controlling the amount of time thatthe etcher is exposed to flat stock 1201, it is possible to produce thecross sectional geometry of each probe as illustrated in FIG. 10.

The resultant superposition of two opposing etch limits 1007 results inthe presence of sharp protrusions or scallops 1003 extending around theperimeter of each etched probe. Note that the distance from scallop base1013 to scallop tip 1015 forms the scallop dimension 1011. Withreference to FIG. 11, there is illustrated a perspective view of a probeend 5005. As can be seen, scallop 1003 extends around the edge 1107 ofthe etched probe 81 including probe tip 1101. Outer probe tip 1105 islocated on opposing sides the flat stock 1201 comprising etched probe 81at the furthest extreme of probe end 5005. Probe tip 1101 can be seen toextend beyond outer probe tip 1105 as a result of the scallop 1003extending around the terminus of probe end 5005. The resulting extensionof probe tip 1101 beyond outer probe tip 1105 allows for better contactwith electrical circuits when etched probe 81 is in use.

Removing the unexposed metal results in an array of probes attached attheir top end. The array of probes is then chemically polished andplated. The probes are then removed from the flat stock 1201 and readiedfor assembly into a probe head. The tops of the probes forming theassembly are lapped while the tips are held referenced to a flat surfaceto bring the probes to the same length.

Embodiment 2—Electroformed Probes

In the second embodiment of the present invention, the mask 73, or anegative of the mask 73, is used to form a metal (e.g., stainless steel)mandrel for use in electroforming an array of probes 81. In thisembodiment, a photoresist is applied to one side of a stainless steelsurface, and the mask 73 is applied over the photoresist. Light is thenapplied to the mask and exposed portions of the photoresist. Thephotoresist is developed and rinsed leaving patterned open or exposedareas on the stainless steel surface corresponding to the probe shape.The patterned stainless steel surface can now be used as a mandrel forelectroforming.

During electroforming, the mandrel is placed in a suitable bath and theproduction or reproduction of the photoresist defined contacts areproduced by electrodeposition of a desired thickness of a metal material(e.g., Nickel or Nickel-Cobalt alloy) onto the exposed portions of themandrel. The photoresist may then be stripped from the mandrel using asuitable solvent. The electrodeposited material is subsequentlyseparated from the mandrel as an array of probes attached at their topend. The individual probes are then removed from the array, ready forassembly into a probe head. The tops of the probes forming the assemblyare lapped while the tips are held referenced to a flat surface to bringthe probes to the same length.

With reference to FIGS. 4-6, there is illustrated the shape of aphoto-defined probe of the present invention as manufactured usingeither the etching or electroforming methods described above.

With reference to FIG. 5, there is illustrated the basic components ofprobe 81. Probe base 5001 is a relatively short and straight expanseconnected to probe shaft 5003. Probe shaft 5003 is a gently curvingexpanse of the probe 81 that terminates in the probe end 5005. Inoperation, it is probe end 5005 that comes in contact with the circuitto be tested. With reference to FIG. 8, as has been described, thephoto-defined probes 81 of the present invention are manufactured to adesired configuration absent mechanical stamping or other processeswhich typically result in residual stresses present in the probes 81. Asused herein, “residual stresses” refers to stresses that remain as theresult of plastic deformation. Conventional probes tend to containresidual stresses resulting from the mechanical stamping and machiningemployed to create a desired probe cross-section. These residualstresses serve to limit the functionality of conventional probes in atleast two primary ways. First, residual stresses cause conventionalprobes to exhibit non-uniform resistive forces in response to a seriesof constant deflections administered to the probe over a period of time.As a result, conventional probes used regularly over a period of timetend to suffer from degradations in their ability to supply constantresistive forces to uniform deflections administered over a period oftime. Second, conventional probes comprised of residual stresses aremore likely to break in response to a deflection. In contrast, thephoto-defined probes 81 of the present invention are created from anetching or electroforming process which does not require mechanicalstamping or machining to achieve desired cross sectionalcharacteristics. As a result, the probes 81 do not contain any residualstresses induced as a result of machining or stamping.

As used herein, “yield strength” refers to the property of a probe todeflect, or yield, in a predominantly linear direction when a force isapplied while retaining the ability to return to its original,non-deflected state absent the application of a force. The greater theyield strength of a probe, the greater the linear deflection that may beexerted upon the probe prior to the probe reaching its yield point,whereupon the probe will not return to its original shape. Applicantsanticipate that the photo-defined probes of the present inventionexhibit increased yield strength compared to probes formed frommechanical processing. Specifically, Applicants anticipate that thephoto-defined probes may be deflected a linear distance approximately20% greater than that distance through which a conventional probe may bedeflected before reaching the yield point.

In addition, it is anticipated that the photo-defined probes of thepresent invention will possess improved spring force uniformity overprobes formed in the conventional manner. As used herein, “spring force”refers to the opposing resistive force generated in a probe which isdeflected through a distance. Specifically, it is anticipated that themaximum difference in the spring forces amongst all of the photo-definedprobes in a probe test head will be approximately 20% less than themaximum difference in the spring forces amongst all of the conventionalprobes in a similar probe test head apparatus.

With reference to FIG. 10, etched probe 81 has a depth 1017 and a width1019. Depth 1017 is typically approximately 3 mils while width 1019 istypically approximately 1 mil. The electroformed probes 81 can be madeto similar dimensions. Because the photo-defined probes 81 (whetheretched or electroformed) are considerably narrower than conventionalprobes 83, when assembled in a probe head the photo-defined probes 81may be assembled spaced approximately every 4 mils while conventionalprobes 83 are typically spaced approximately every 8 mils. Because thecenter-center distance between the photo-defined probes of the presentinvention assembled in a probe head can be as small as 4 mils, asopposed to the approximately 8 mils required of conventional probes, thephoto-defined probes may be used for testing smaller integrated circuitswherein the distance between contacts on the integrated circuit wafer isas small as approximately 4 mils.

In addition, because a plurality of photo-defined probes 81 is fashionedfrom a single flat stock 1201 (in the case of etching) or from a singleelectroforming process (in the case of electroforming) using a commonmask 73, each etched probe 81 is substantially similar in its physicalcharacteristics to each and every other etched probe 81.

EXAMPLE 1

The following example details parameters preferable to practicing anembodiment of the present invention. Preferably, there is practiced aplurality of steps including material preparation, photo masking,etching, chemical polishing, plating, and a process of individualizingthe probes thus formed. As used herein, “DI” is a descriptor meaningde-ionized. In addition, as used herein, “UX DI” refers toultrasonically agitated de-ionized water.

To prepare the material out of which the probes were to be formed, BeCu17200 Flat stock was cut into squares with side lengths approximatingfour inches. The flat stock was then cleaned with Citra-solv (byCitra-Solv, LLC of Danbury, Conn.)/DI H2O 20 ML/1 L (UX 15 Min.). Thesurface of the flat stock was then air blown dry and the resultingpackage was then heat hardened in a vacuum for approximately two hoursat 600° F.

Next, the prepared material was photo masked. To accomplish the photomasking, the material was again cleaned with Clean Citra-Solv/DI H2O 20ML/1 L (UX 15 Min. ). Next the material was provided a dip coat with awithdraw rate of 13.3 Sec./1 in. (Shipley SP2029-1) Thinned to 35Zon/Sec. at 21° C. The material was then dried for approximately 30minutes at 90° C. and allowed to cool at room temperature underconditions of greater than fifty percent relative humidity. Next, theprepared surface of the material was exposed to approximately 100milijules 365 nanometer wavelength UV light. The surface exposed to thelight was then developed for approximately 1 min 30 sec (Shipley 303developer, by Shipley Inc. of Newton Mass., at 85° F.). Lastly, theprepared surface was rinsed in cascading DI water for 15 minutes thenair blown dry and stored.

Next, etching was performed using a Marseco Mod.# CES-24, by MarsecoInc. of Huntington Beach, Calif. Hi-speed circuit etching was thenperformed using Phibro-Tech High Speed Circuit etching solution with thefollowing parameter settings:

-   -   Temperature setting 128 deg. F. (act 127 deg. F.)    -   Pump speed (Pump #1—45%) (Pump #2—73%)    -   Conveyor (11%)    -   Oscillation (Normal)        A foil test piece was then mounted to the carrier and run        through the etcher. The critical dimensions of the resultant        parts created from the foil test piece were then measured and        adjustments made if necessary. After adjustments were made, the        remaining foils were run through the etcher at 30 sec.        intervals.

Next a chemical polish/bright dip was applied to the probes formed frometching. The probes were submerged in PNA Etch in a 2L beaker at145-150° F. while stirring. The solution was comprised as follows:

Phosphoric Acid  760 ML of a 98% solution Nitric Acid  40 ML of a 69-70%solution Acetic Acid 1200 ML of a 60% solutionFirst, the etch rate was established using a test piece of material.Next, the probe material was etched to remove 0.0001″ Next the materialwas rinsed in hot DI, in UX DI for approximately 15 minutes and a DIcascade for approximately 2 minutes. Lastly, the probes are oven driedat 100° C. until dry.

Next, the probes were plated using a Pallamerse Immersion Palladium 5%solution, by Technic Inc. of Cranston R.I., and a Pd activator 25%solution manufactured by Technic Inc. and a Vertrel solvent by DupontFluoroproducts of Wilmington, Del. The probes were then weighed andtheir weights recorded. The probes were then washed in the Vertrelsolvent for approximately two minutes. Next, the probes were rinsed inDI H₂O for one minute and in a 10% sulfuric acid solution for twominutes followed by another two minute rinse in DI H₂O. The probes werethen immersed for 30 seconds in the Technic Pd activator and once againrinsed in DI H₂O for 30 seconds. The probes were then immersed for 45minutes in Technic immersion Palladium while stirring slowly, rinsedwith running DI H₂O and dried. The probes were then re-weighed and theirweights recorded.

Lastly, the probes were individualized. A sample of the probes,preferably five or six probes, is tested to measure the grams ofresistive force generated within each of the probes when deflected fromone to eight millimeters in one millimeter increments. The results onone such test group of probes is illustrated in Table 1. The results ofthe test were used to assess the uniformity of the probes created fromany one initial flat stock as well as conformity to desired properties.The probes were then put in a vile and labeled with tip and shankdimension.

TABLE 1 Dim. Force 1^(st) 1^(st) Sample Touch Touch 1 mil 2 mil 3 mil 4mil 5 mil 6 mil 7 mil 8 mil 1 0 .0050 4.80 9.80 12.95 15.63 17.86 20.1021.41 21.72 2 0 .0053 4.50 8.80 12.23 15.21 17.80 19.81 21.60 18.02 3 0.0051 4.80 9.90 13.60 17.00 19.70 21.30 22.31 23.31 4 0 .0056 4.91 9.6013.92 17.70 20.30 22.80 24.80 25.41 5 0 .0045 5.80 11.00 14.90 17.3019.60 21.72 22.22 22.50 6 0 .0053 4.82 8.66 12.23 14.92 17.30 19.5021.26 22.15

There is therefore provided herein a process for mass producingminiature micro probes or electrical contacts for use in the testing ofsemiconductor chips having the following advantages over theconventional probe manufacturing process. First the method of thepresent invention provides improved uniformity and dimensional accuracybetween the probes. The glass mask determines the geometry of theprobes, eliminating mechanical variances between the probes. As aresult, the stiffness of the probes are more uniform, allowing for abalanced contact force across the array.

In addition, there are no stresses induced in the probes duringfabrication, resulting in improved probe strength and endurance. Theconventional stamping process results in residual stresses, causingreduced fatigue life. The stresses can change over time, causing changesin probe stiffness.

The present invention provides for lower cost and lead-time inmanufacturing. Many probes are manufactured simultaneously, and the tipgeometry can be made via the etching or electroforming process ratherthan as a follow-on process step. The polishing and plating processesare also done simultaneously.

The probe design of the present invention can be easily modified. Whereetching is used, the spring rate can be controlled by varying theartwork used to create the glass mask, and by the thickness of the flatmetal stock selected. Where electroforming is used, the spring rate canbe controlled by varying the artwork used to create the glass mask andby controlling the thickness of the electroform. In either case, newdesigns can be made by simply creating a new mask. There is no need forexpensive and time consuming re-tooling.

Lastly, the etched or electroformed probes produced by the method forthe present invention do not require a swage to achieve the requiredstiffness. As a result, the probes can be placed closer together,allowing for a denser array.

1. A method of fabricating a plurality of micro probes comprising thesteps of: providing one or more masks, each of said one or more masksincluding a plurality of probe shapes, each of said plurality of probeshapes including a probe base, a probe shaft connected to said probebase, a probe end connected to said probe shaft, and one or more raisedsurfaces on at least one of said probe base, said probe end and saidprobe shaft; applying a photoresist to a side of a first metal material;overlaying said mask on said side of said first metal material; exposingsaid photoresist to light passed through said mask; developing saidphotoresist; removing a portion of said photoresist to expose a portionof said first metal material, electroforming a second metal material onsaid exposed portions of said first metal material; and removing saidsecond metal material to produce a plurality of probes, each of saidplurality of probes including a probe base, a probe shaft connected tosaid probe base, a probe end connected to said probe shaft, and one ormore raised surfaces on at least one of said probe base, said probe end,and said probe shaft.
 2. The method of claim 1 wherein said firstmaterial is stainless steel.
 3. The method of claim 1 wherein saidsecond material is selected from one of Nickel and Nickel-Cobalt alloy.4. A micro probe comprising: a probe base having a generally uniformthickness bounded by a plurality of edges and extending for asubstantially straight length in a plane; a probe shaft connected tosaid probe base said probe shaft of said generally uniform thickness,bounded by a plurality of edges, and extending along a curved expansewithin said plane; a probe end connected to said probe shaft said probeend of said generally uniform thickness, bounded by a plurality ofedges, and extending for a substantially straight distance within saidplane said straight distance being approximately parallel to saidstraight length; and one or more raised surfaces positioned on at leastone of said probe base, said probe shaft and said probe end, whereinsaid one or more raised surfaces are formed from a mechanical process.5. The micro probe of claim 4 wherein said uniform thickness is between2 mils and 5 mils.
 6. The micro probe of claim 5 wherein said uniformthickness is between 3 mils and 4 mils.
 7. The micro probe of claim 4wherein said mechanical process is an electroforming process.